There are circumstances in which you want to control which broadcast packets and which protocols are forwarded. You do this with helper addresses and the forward-protocol commands.

The ip helper-address interface subcommand tells the router to forward UDP broadcasts, including BootP, received on this interface. (UDP is the connectionless alternative to TCP at the Transport Layer.) Use the ip helper-address interface subcommand to specify the destination address for forwarding broadcast packets. Full command syntax follows.